Humidity measuring device



May 28, 1957 H. F. DALGLISH HUMIDITY MEASURING DEVICE 2 Sheets-Sheet 1Filed Feb. 8, 1954 m W h N wk m V W A A a a & wf f Am r. b r e @Q m a aww May 28, 1957 H. F. DALGLISH HUMIDITY MEASURING DEVICE Filed Feb. 8,1954 2 Sheets-Sheet 2 INVENTOR He rberf F. Da/y/ish ATTORNEY UnitedStates Patent HUMIDITY MEASURING DEVICE Herbert F. Dalglish, St. Paul,Minn. Application February 8, 1954, Serial No. 463,67

Claims. (Cl. 73-73) For example, when grain is stored in elevators ofconsiderable depth the humidity of the material is of utmost importancein indicating the quality of the grain. However, the action of the grainwhen inserted into the elevator or removed therefrom tends to injure ordestroy circuits of usualtype. .If such circuits are enclosed in rigidhousings they are not readily susceptible to the humidity conditions insurrounding bodies of material. It is necessary that ambient air alfectthe measurement and this is impractical in a rigid housing unless it isperforated throughout its length. Rigid housings are much moresusceptible to the action of forces such as those produced by theswirling of grain within the elevator as it is inserted and Withdrawn.The present structure is designed to obviate these difficulties.

These and other objects and novel features of the invention will be moreclearly and fully set forth in the following specification and claims.

In the drawings forming a part of the specification:

Figure l is a longitudinal sectional view diagrammatically through aWire rope cable showing the arrangement of the parts.

Figure 2 is a cross sectional view showing the arrangement of theconductors relative to the cable and the humidity measuring capsulestherein.

Figure 3 is a sectional View through the wire rope cable at a pointintermediate the capsules showing the core which fills intermediate thecapsules.

Figure 4 illustrates diagrammatically the manner in which a series ofhumidity measuring capsules may be mounted in a wire rope cable.

Figure 5 is a diagrammatic view showing a wiring diagram which may beused for the indication of humidity at various points throughout thelength of the cable.

Figure 6 is a sectional view through a modified form of construction.

At the outset it should be understood that in using the term wire ropecable it is not desired to limit the structure to any particular form ofwires encircling the core of the apparatus. The cable may be formed ofwires which are twisted, laid or braided and their particular formationis not important in the present invention.

The humidity measuring device A includes a wire rope cable having aseries or" angularly spaced strands it), each strand being formed of aplurality of twisted wires 11. The twisting of the wires provides smallspaces between the wires. The strands when twisted are not entirely incontact so that the cable is porous to a certain extent.

The cable thus formed is provided with a core constructed as best shownin Figure l of the drawings. The core includes a series oflongitudinally spaced capsules 12'formedof a woven or punctured plasticmaterial as a vinyl polymer or other resinous material containing ahydroscopic salt or like agent which varies in electrical conductivityin proportion to the moisture content of the material. Accordingly, whenthere is more moisture in the air the material 13 which is a hydroscopicsalt as calcium chloride or the like within the capsule 12 becomes moreor less electrically conductive.

Each capsule 12 also includes a pair of spaced wires or electrodes 14and 15. The spacing between these electrodes is normally uniform in allof the capsules so as to provide a predetermined length of material 13between these electrodes. The electrodes 15 provide a means ofdeterminingthe humidity when properly connected to measure the varyingresistance between the electrodes.

As shown in'Figure 2 of the drawings, the capsules 12 are of smalleroutside diameter than the inner diameter of the wire rope strands '10and conductors such as illustrated by the numeral 16 encircle thecapsules 12. These conductors 16, illustratively representative ofconductors 20, 21, 22 and 24, connect the electrodes of the variousspaced capsules at an end of the cable to form independent circuits sothat'the humidity may be measured at various points by each capsulethroughout the length of the cable. In usualconstruction one wire ofeach capsule electrode is common throughout the cable while the otherelectrode is connected by individual conductors leading to .the cableend.

As shown in Figures 1 and 3 of the drawings, a core or filler 17 extendsbetween the various capsules 12 so as to provide a core of uniform size.This filler 17 may be of any suitable flexible material of about thesame outside diameter as the capsule 12. In actual practice ma terialsuch as cotton rope and the like has been used for this purpose. Withsuch an arrangement the wires usually extend about the periphery of thetiller as well as about the periphery of the capsules 12.

Figure 6 of the drawings shows a modified form of construction in whichthe interior of the cable is extruded with a material through whichmoisture may pass. In other words, in the arrangement shown in Figure 6,the interior of the cable is filled with a material which is eitherporous to provide passage of air therethrough or else is of materialwhich will conduct moisture to the cap sules and which will not seal thecapsules so that they will not react properly to ambient humidityconditions. The filling material 19 w 'ch may be, for example, a porousnylon, Formvar (found in ASTM) or other insulating material as asilicone wax (Teflon) shown in Figure 6 will encircle the capsules andwill till the space between the various conductors within the cablestrands.

With the arrangement illustrated, it is possible to measure humidity atvarious points throughout the length of the cable. As indicated inFigure 5 of the drawings a common wire such as 20 is connected to oneelectrode 14 of each of the capsules 12. Conductors 21, 22, 23 and 24,extend from the other electrodes 15 to the end of the cable. A suitablehumidity measuring apparatus is employed, this apparatus being showndiagrammatically in the figure. A battery 25 is connected to the commonWire 20 and a potentiometer or variable resistance 26 and a milliamperemeter 27 are connected in series between the other terminal of thebattery and a switch 29. The various conductors 21, 22, 23 and 24, areconnected to switch terminals 34, 33, 32, and 31, respectively. Theseterminals can be selectively connected to the other switch terminal 35.The humidity is measured in the uppermost cell 12 illustrated in Figure5, for example, by connecting the switch terminals 31 and 35, as shownin dotted line.

I have found that any control cable is of considerable value indetermining the physical condition of grain at various elevationsthrough a bin or tank. The cable may similarly be used for numerousother purposes where it is desirable to measure humidity at variousspaced points.

The structure is simple in nature, inexpensive to produce a and serves anovel and unusual purpose.

In accordance with the patent statutes, I have described the principlesof construction and operation of my conductors connected to each saidelement to form an independent circuit to each said element, a flexiblewire cable pervious to air, and means supporting said elements inlongitudinally spaced relation said cable, whereby said elements maysense humidity of air outside of the cable, and whereby the humidity atany of said elements may be determined.

2. The structure described in claim 1 and including a core fillingbetween said elements.

3. The structure described in claim 1 and including a core within saidcable between said elements, said core being of substantially equaldiameter to said elements.

4. A humidity measuring cable including a plurality of humiditysensitive variable resistance means, a hollow air pervious cableenclosing said means at substantially equally spaced positions along thelength of said cable, and independent conductor means in said cableconnected to said each humidity sensitive means and extendinglongitudinally of said cable to an end thereof, said conductors formingan independent circuit to each said humidity sensitive means, wherebythe humidity may be independently sensed at any of said positionsthroughout the length of the cable from said one end thereof.

5. A humidity measuring cable including a series of spaced humiditysensitive capsules capable of independently measuring humidity bychanges in electrical resistance, means enclosing said elements, saidlast named means comprising a flexible cable pervions to air, andconductor means connected to each of said elements and extending to oneend of said cable and forming an independent circuit to each capsulewhereby the resistance of each said element may be measured from saidone end of said cable.

References Cited in the file of this patent UNITED STATES PATENTS2,285,421 Dunmore June 9, 1942 2,526,636 Colman Oct. 24, 1950 2,663,190Ilgenfritz Dec. 22, 1953 2,742,780 Feigal Apr. 24, 1956 FOREIGN PATENTS275,036 Great Britain Aug. 4, 1927 692,641 Germany June 24, 1940

